1. Field of the Invention
Embodiments of the present invention generally relate to polyurethane production; more specifically to polyol prepolymers useful in polyurethane foam production.
2. Description of the Related Art
Polyether polyols based on the polymerization of alkylene oxides, polyester polyols, or combinations thereof, are together with isocyanates the major components of a polyurethane system. One class of polyols are conventional petroleum-based polyols, and another class are those polyols made from vegetable oils or other renewable feedstocks. These polyols are also called natural oil based polyols (NOBP). Natural oil based polyols may be sold and marketed as a component of polyol blends which often also may include conventional petroleum-based polyols. Because the natural oil based polyols contain fatty groups, i.e. long chains of saturated and/or unsaturated hydrocarbons, the natural oil based polyols have hydrophobic characteristics and may therefore not be miscible or otherwise compatible with conventional petroleum-based polyols. Furthermore, natural oil based polyols may be lower in density than conventional petroleum based polyether polyols. This difference in densities may also be a contributing factor to phase separation and haziness of the polyol blends.
The quality of the polyol blends may be linked to the quality of the polyurethane product. For example, phase separation in the polyol blends and the blend's incompatibility with water may result in polyurethane foams exhibiting shrinkage, large shot-holes, or large pin-holes. Polyol blend quality also may be a factor when natural oil based polyols are used as alternatives to conventional polyester polyols in the manufacture of flexible slabstock foams which are flame laminated to fabric or other surfaces. A regular cell structure of such foams may be preferred for optimized adhesion and optical/visual character of the composite, often used in upholstery of automotive seating or in garments.
Therefore, a natural oil based polyol which is more compatible with water and/or other polyols and is able to give regular foam cell structure is needed.